drivers/i2c/soft_i2c.c

   1 // SPDX-License-Identifier: GPL-2.0+
   2 /*
   3  * (C) Copyright 2009
   4  * Heiko Schocher, DENX Software Engineering, hs@denx.de.
   5  * Changes for multibus/multiadapter I2C support.
   6  *
   7  * (C) Copyright 2001, 2002
   8  * Wolfgang Denk, DENX Software Engineering, wd@denx.de.
   9  *
  10  * This has been changed substantially by Gerald Van Baren, Custom IDEAS,
  11  * vanbaren@cideas.com.  It was heavily influenced by LiMon, written by
  12  * Neil Russell.
  13  *
  14  * NOTE: This driver should be converted to driver model before June 2017.
  15  * Please see doc/driver-model/i2c-howto.rst for instructions.
  16  */
  17
  18 #include <common.h>
  19 #if defined(CONFIG_AT91FAMILY)
  20 #include <asm/io.h>
  21 #include <asm/arch/hardware.h>
  22 #include <asm/arch/at91_pio.h>
  23 #ifdef CONFIG_ATMEL_LEGACY
  24 #include <asm/arch/gpio.h>
  25 #endif
  26 #endif
  27 #include <i2c.h>
  28 #include <asm/global_data.h>
  29 #include <linux/delay.h>
  30
  31 #if defined(CONFIG_SOFT_I2C_GPIO_SCL)
  32 # include <asm/gpio.h>
  33
  34 # ifndef I2C_GPIO_SYNC
  35 #  define I2C_GPIO_SYNC
  36 # endif
  37
  38 # ifndef I2C_INIT
  39 #  define I2C_INIT \
  40         do { \
  41                 gpio_request(CONFIG_SOFT_I2C_GPIO_SCL, "soft_i2c"); \
  42                 gpio_request(CONFIG_SOFT_I2C_GPIO_SDA, "soft_i2c"); \
  43         } while (0)
  44 # endif
  45
  46 # ifndef I2C_ACTIVE
  47 #  define I2C_ACTIVE do { } while (0)
  48 # endif
  49
  50 # ifndef I2C_TRISTATE
  51 #  define I2C_TRISTATE do { } while (0)
  52 # endif
  53
  54 # ifndef I2C_READ
  55 #  define I2C_READ gpio_get_value(CONFIG_SOFT_I2C_GPIO_SDA)
  56 # endif
  57
  58 # ifndef I2C_SDA
  59 #  define I2C_SDA(bit) \
  60         do { \
  61                 if (bit) \
  62                         gpio_direction_input(CONFIG_SOFT_I2C_GPIO_SDA); \
  63                 else \
  64                         gpio_direction_output(CONFIG_SOFT_I2C_GPIO_SDA, 0); \
  65                 I2C_GPIO_SYNC; \
  66         } while (0)
  67 # endif
  68
  69 # ifndef I2C_SCL
  70 #  define I2C_SCL(bit) \
  71         do { \
  72                 gpio_direction_output(CONFIG_SOFT_I2C_GPIO_SCL, bit); \
  73                 I2C_GPIO_SYNC; \
  74         } while (0)
  75 # endif
  76
  77 # ifndef I2C_DELAY
  78 #  define I2C_DELAY udelay(5)   /* 1/4 I2C clock duration */
  79 # endif
  80
  81 #endif
  82
  83 /* #define      DEBUG_I2C       */
  84
  85 DECLARE_GLOBAL_DATA_PTR;
  86
  87 #ifndef I2C_SOFT_DECLARATIONS
  88 #  define I2C_SOFT_DECLARATIONS
  89 #endif
  90
  91 #if !defined(CONFIG_SYS_I2C_SOFT_SPEED)
  92 #define CONFIG_SYS_I2C_SOFT_SPEED CONFIG_SYS_I2C_SPEED
  93 #endif
  94 #if !defined(CONFIG_SYS_I2C_SOFT_SLAVE)
  95 #define CONFIG_SYS_I2C_SOFT_SLAVE CONFIG_SYS_I2C_SLAVE
  96 #endif
  97
  98 /*-----------------------------------------------------------------------
  99  * Definitions
 100  */
 101 #define RETRIES         0
 102
 103 #define I2C_ACK         0               /* PD_SDA level to ack a byte */
 104 #define I2C_NOACK       1               /* PD_SDA level to noack a byte */
 105
 106
 107 #ifdef DEBUG_I2C
 108 #define PRINTD(fmt,args...)     do {    \
 109                 printf (fmt ,##args);   \
 110         } while (0)
 111 #else
 112 #define PRINTD(fmt,args...)
 113 #endif
 114
 115 /*-----------------------------------------------------------------------
 116  * Local functions
 117  */
 118 #if !defined(CONFIG_SYS_I2C_INIT_BOARD)
 119 static void  send_reset (void);
 120 #endif
 121 static void  send_start (void);
 122 static void  send_stop  (void);
 123 static void  send_ack   (int);
 124 static int   write_byte (uchar byte);
 125 static uchar read_byte  (int);
 126
 127 #if !defined(CONFIG_SYS_I2C_INIT_BOARD)
 128 /*-----------------------------------------------------------------------
 129  * Send a reset sequence consisting of 9 clocks with the data signal high
 130  * to clock any confused device back into an idle state.  Also send a
 131  * <stop> at the end of the sequence for belts & suspenders.
 132  */
 133 static void send_reset(void)
 134 {
 135         I2C_SOFT_DECLARATIONS   /* intentional without ';' */
 136         int j;
 137
 138         I2C_SCL(1);
 139         I2C_SDA(1);
 140 #ifdef  I2C_INIT
 141         I2C_INIT;
 142 #endif
 143         I2C_TRISTATE;
 144         for(j = 0; j < 9; j++) {
 145                 I2C_SCL(0);
 146                 I2C_DELAY;
 147                 I2C_DELAY;
 148                 I2C_SCL(1);
 149                 I2C_DELAY;
 150                 I2C_DELAY;
 151         }
 152         send_stop();
 153         I2C_TRISTATE;
 154 }
 155 #endif
 156
 157 /*-----------------------------------------------------------------------
 158  * START: High -> Low on SDA while SCL is High
 159  */
 160 static void send_start(void)
 161 {
 162         I2C_SOFT_DECLARATIONS   /* intentional without ';' */
 163
 164         I2C_DELAY;
 165         I2C_SDA(1);
 166         I2C_ACTIVE;
 167         I2C_DELAY;
 168         I2C_SCL(1);
 169         I2C_DELAY;
 170         I2C_SDA(0);
 171         I2C_DELAY;
 172 }
 173
 174 /*-----------------------------------------------------------------------
 175  * STOP: Low -> High on SDA while SCL is High
 176  */
 177 static void send_stop(void)
 178 {
 179         I2C_SOFT_DECLARATIONS   /* intentional without ';' */
 180
 181         I2C_SCL(0);
 182         I2C_DELAY;
 183         I2C_SDA(0);
 184         I2C_ACTIVE;
 185         I2C_DELAY;
 186         I2C_SCL(1);
 187         I2C_DELAY;
 188         I2C_SDA(1);
 189         I2C_DELAY;
 190         I2C_TRISTATE;
 191 }
 192
 193 /*-----------------------------------------------------------------------
 194  * ack should be I2C_ACK or I2C_NOACK
 195  */
 196 static void send_ack(int ack)
 197 {
 198         I2C_SOFT_DECLARATIONS   /* intentional without ';' */
 199
 200         I2C_SCL(0);
 201         I2C_DELAY;
 202         I2C_ACTIVE;
 203         I2C_SDA(ack);
 204         I2C_DELAY;
 205         I2C_SCL(1);
 206         I2C_DELAY;
 207         I2C_DELAY;
 208         I2C_SCL(0);
 209         I2C_DELAY;
 210 }
 211
 212 /*-----------------------------------------------------------------------
 213  * Send 8 bits and look for an acknowledgement.
 214  */
 215 static int write_byte(uchar data)
 216 {
 217         I2C_SOFT_DECLARATIONS   /* intentional without ';' */
 218         int j;
 219         int nack;
 220
 221         I2C_ACTIVE;
 222         for(j = 0; j < 8; j++) {
 223                 I2C_SCL(0);
 224                 I2C_DELAY;
 225                 I2C_SDA(data & 0x80);
 226                 I2C_DELAY;
 227                 I2C_SCL(1);
 228                 I2C_DELAY;
 229                 I2C_DELAY;
 230
 231                 data <<= 1;
 232         }
 233
 234         /*
 235          * Look for an <ACK>(negative logic) and return it.
 236          */
 237         I2C_SCL(0);
 238         I2C_DELAY;
 239         I2C_SDA(1);
 240         I2C_TRISTATE;
 241         I2C_DELAY;
 242         I2C_SCL(1);
 243         I2C_DELAY;
 244         I2C_DELAY;
 245         nack = I2C_READ;
 246         I2C_SCL(0);
 247         I2C_DELAY;
 248         I2C_ACTIVE;
 249
 250         return(nack);   /* not a nack is an ack */
 251 }
 252
 253 /*-----------------------------------------------------------------------
 254  * if ack == I2C_ACK, ACK the byte so can continue reading, else
 255  * send I2C_NOACK to end the read.
 256  */
 257 static uchar read_byte(int ack)
 258 {
 259         I2C_SOFT_DECLARATIONS   /* intentional without ';' */
 260         int  data;
 261         int  j;
 262
 263         /*
 264          * Read 8 bits, MSB first.
 265          */
 266         I2C_TRISTATE;
 267         I2C_SDA(1);
 268         data = 0;
 269         for(j = 0; j < 8; j++) {
 270                 I2C_SCL(0);
 271                 I2C_DELAY;
 272                 I2C_SCL(1);
 273                 I2C_DELAY;
 274                 data <<= 1;
 275                 data |= I2C_READ;
 276                 I2C_DELAY;
 277         }
 278         send_ack(ack);
 279
 280         return(data);
 281 }
 282
 283 /*-----------------------------------------------------------------------
 284  * Initialization
 285  */
 286 static void soft_i2c_init(struct i2c_adapter *adap, int speed, int slaveaddr)
 287 {
 288 #if defined(CONFIG_SYS_I2C_INIT_BOARD)
 289         /* call board specific i2c bus reset routine before accessing the   */
 290         /* environment, which might be in a chip on that bus. For details   */
 291         /* about this problem see doc/I2C_Edge_Conditions.                  */
 292         i2c_init_board();
 293 #else
 294         /*
 295          * WARNING: Do NOT save speed in a static variable: if the
 296          * I2C routines are called before RAM is initialized (to read
 297          * the DIMM SPD, for instance), RAM won't be usable and your
 298          * system will crash.
 299          */
 300         send_reset ();
 301 #endif
 302 }
 303
 304 /*-----------------------------------------------------------------------
 305  * Probe to see if a chip is present.  Also good for checking for the
 306  * completion of EEPROM writes since the chip stops responding until
 307  * the write completes (typically 10mSec).
 308  */
 309 static int soft_i2c_probe(struct i2c_adapter *adap, uint8_t addr)
 310 {
 311         int rc;
 312
 313         /*
 314          * perform 1 byte write transaction with just address byte
 315          * (fake write)
 316          */
 317         send_start();
 318         rc = write_byte ((addr << 1) | 0);
 319         send_stop();
 320
 321         return (rc ? 1 : 0);
 322 }
 323
 324 /*-----------------------------------------------------------------------
 325  * Read bytes
 326  */
 327 static int  soft_i2c_read(struct i2c_adapter *adap, uchar chip, uint addr,
 328                         int alen, uchar *buffer, int len)
 329 {
 330         int shift;
 331         PRINTD("i2c_read: chip %02X addr %02X alen %d buffer %p len %d\n",
 332                 chip, addr, alen, buffer, len);
 333
 334 #ifdef CONFIG_SYS_I2C_EEPROM_ADDR_OVERFLOW
 335         /*
 336          * EEPROM chips that implement "address overflow" are ones
 337          * like Catalyst 24WC04/08/16 which has 9/10/11 bits of
 338          * address and the extra bits end up in the "chip address"
 339          * bit slots. This makes a 24WC08 (1Kbyte) chip look like
 340          * four 256 byte chips.
 341          *
 342          * Note that we consider the length of the address field to
 343          * still be one byte because the extra address bits are
 344          * hidden in the chip address.
 345          */
 346         chip |= ((addr >> (alen * 8)) & CONFIG_SYS_I2C_EEPROM_ADDR_OVERFLOW);
 347
 348         PRINTD("i2c_read: fix addr_overflow: chip %02X addr %02X\n",
 349                 chip, addr);
 350 #endif
 351
 352         /*
 353          * Do the addressing portion of a write cycle to set the
 354          * chip's address pointer.  If the address length is zero,
 355          * don't do the normal write cycle to set the address pointer,
 356          * there is no address pointer in this chip.
 357          */
 358         send_start();
 359         if(alen > 0) {
 360                 if(write_byte(chip << 1)) {     /* write cycle */
 361                         send_stop();
 362                         PRINTD("i2c_read, no chip responded %02X\n", chip);
 363                         return(1);
 364                 }
 365                 shift = (alen-1) * 8;
 366                 while(alen-- > 0) {
 367                         if(write_byte(addr >> shift)) {
 368                                 PRINTD("i2c_read, address not <ACK>ed\n");
 369                                 return(1);
 370                         }
 371                         shift -= 8;
 372                 }
 373
 374                 /* Some I2C chips need a stop/start sequence here,
 375                  * other chips don't work with a full stop and need
 376                  * only a start.  Default behaviour is to send the
 377                  * stop/start sequence.
 378                  */
 379 #ifdef CONFIG_SOFT_I2C_READ_REPEATED_START
 380                 send_start();
 381 #else
 382                 send_stop();
 383                 send_start();
 384 #endif
 385         }
 386         /*
 387          * Send the chip address again, this time for a read cycle.
 388          * Then read the data.  On the last byte, we do a NACK instead
 389          * of an ACK(len == 0) to terminate the read.
 390          */
 391         write_byte((chip << 1) | 1);    /* read cycle */
 392         while(len-- > 0) {
 393                 *buffer++ = read_byte(len == 0);
 394         }
 395         send_stop();
 396         return(0);
 397 }
 398
 399 /*-----------------------------------------------------------------------
 400  * Write bytes
 401  */
 402 static int  soft_i2c_write(struct i2c_adapter *adap, uchar chip, uint addr,
 403                         int alen, uchar *buffer, int len)
 404 {
 405         int shift, failures = 0;
 406
 407         PRINTD("i2c_write: chip %02X addr %02X alen %d buffer %p len %d\n",
 408                 chip, addr, alen, buffer, len);
 409
 410         send_start();
 411         if(write_byte(chip << 1)) {     /* write cycle */
 412                 send_stop();
 413                 PRINTD("i2c_write, no chip responded %02X\n", chip);
 414                 return(1);
 415         }
 416         shift = (alen-1) * 8;
 417         while(alen-- > 0) {
 418                 if(write_byte(addr >> shift)) {
 419                         PRINTD("i2c_write, address not <ACK>ed\n");
 420                         return(1);
 421                 }
 422                 shift -= 8;
 423         }
 424
 425         while(len-- > 0) {
 426                 if(write_byte(*buffer++)) {
 427                         failures++;
 428                 }
 429         }
 430         send_stop();
 431         return(failures);
 432 }
 433
 434 /*
 435  * Register soft i2c adapters
 436  */
 437 U_BOOT_I2C_ADAP_COMPLETE(soft00, soft_i2c_init, soft_i2c_probe,
 438                          soft_i2c_read, soft_i2c_write, NULL,
 439                          CONFIG_SYS_I2C_SOFT_SPEED, CONFIG_SYS_I2C_SOFT_SLAVE,
 440                          0)
 441 #if defined(I2C_SOFT_DECLARATIONS2)
 442 U_BOOT_I2C_ADAP_COMPLETE(soft01, soft_i2c_init, soft_i2c_probe,
 443                          soft_i2c_read, soft_i2c_write, NULL,
 444                          CONFIG_SYS_I2C_SOFT_SPEED_2,
 445                          CONFIG_SYS_I2C_SOFT_SLAVE_2,
 446                          1)
 447 #endif
 448 #if defined(I2C_SOFT_DECLARATIONS3)
 449 U_BOOT_I2C_ADAP_COMPLETE(soft02, soft_i2c_init, soft_i2c_probe,
 450                          soft_i2c_read, soft_i2c_write, NULL,
 451                          CONFIG_SYS_I2C_SOFT_SPEED_3,
 452                          CONFIG_SYS_I2C_SOFT_SLAVE_3,
 453                          2)
 454 #endif
 455 #if defined(I2C_SOFT_DECLARATIONS4)
 456 U_BOOT_I2C_ADAP_COMPLETE(soft03, soft_i2c_init, soft_i2c_probe,
 457                          soft_i2c_read, soft_i2c_write, NULL,
 458                          CONFIG_SYS_I2C_SOFT_SPEED_4,
 459                          CONFIG_SYS_I2C_SOFT_SLAVE_4,
 460                          3)
 461 #endif
 462 #if defined(I2C_SOFT_DECLARATIONS5)
 463 U_BOOT_I2C_ADAP_COMPLETE(soft04, soft_i2c_init, soft_i2c_probe,
 464                          soft_i2c_read, soft_i2c_write, NULL,
 465                          CONFIG_SYS_I2C_SOFT_SPEED_5,
 466                          CONFIG_SYS_I2C_SOFT_SLAVE_5,
 467                          4)
 468 #endif
 469 #if defined(I2C_SOFT_DECLARATIONS6)
 470 U_BOOT_I2C_ADAP_COMPLETE(soft05, soft_i2c_init, soft_i2c_probe,
 471                          soft_i2c_read, soft_i2c_write, NULL,
 472                          CONFIG_SYS_I2C_SOFT_SPEED_6,
 473                          CONFIG_SYS_I2C_SOFT_SLAVE_6,
 474                          5)
 475 #endif
 476 #if defined(I2C_SOFT_DECLARATIONS7)
 477 U_BOOT_I2C_ADAP_COMPLETE(soft06, soft_i2c_init, soft_i2c_probe,
 478                          soft_i2c_read, soft_i2c_write, NULL,
 479                          CONFIG_SYS_I2C_SOFT_SPEED_7,
 480                          CONFIG_SYS_I2C_SOFT_SLAVE_7,
 481                          6)
 482 #endif
 483 #if defined(I2C_SOFT_DECLARATIONS8)
 484 U_BOOT_I2C_ADAP_COMPLETE(soft07, soft_i2c_init, soft_i2c_probe,
 485                          soft_i2c_read, soft_i2c_write, NULL,
 486                          CONFIG_SYS_I2C_SOFT_SPEED_8,
 487                          CONFIG_SYS_I2C_SOFT_SLAVE_8,
 488                          7)
 489 #endif
 490 #if defined(I2C_SOFT_DECLARATIONS9)
 491 U_BOOT_I2C_ADAP_COMPLETE(soft08, soft_i2c_init, soft_i2c_probe,
 492                          soft_i2c_read, soft_i2c_write, NULL,
 493                          CONFIG_SYS_I2C_SOFT_SPEED_9,
 494                          CONFIG_SYS_I2C_SOFT_SLAVE_9,
 495                          8)
 496 #endif
 497 #if defined(I2C_SOFT_DECLARATIONS10)
 498 U_BOOT_I2C_ADAP_COMPLETE(soft09, soft_i2c_init, soft_i2c_probe,
 499                          soft_i2c_read, soft_i2c_write, NULL,
 500                          CONFIG_SYS_I2C_SOFT_SPEED_10,
 501                          CONFIG_SYS_I2C_SOFT_SLAVE_10,
 502                          9)
 503 #endif
 504 #if defined(I2C_SOFT_DECLARATIONS11)
 505 U_BOOT_I2C_ADAP_COMPLETE(soft10, soft_i2c_init, soft_i2c_probe,
 506                          soft_i2c_read, soft_i2c_write, NULL,
 507                          CONFIG_SYS_I2C_SOFT_SPEED_11,
 508                          CONFIG_SYS_I2C_SOFT_SLAVE_11,
 509                          10)
 510 #endif
 511 #if defined(I2C_SOFT_DECLARATIONS12)
 512 U_BOOT_I2C_ADAP_COMPLETE(soft11, soft_i2c_init, soft_i2c_probe,
 513                          soft_i2c_read, soft_i2c_write, NULL,
 514                          CONFIG_SYS_I2C_SOFT_SPEED_12,
 515                          CONFIG_SYS_I2C_SOFT_SLAVE_12,
 516                          11)
 517 #endif